The present invention relates to on-board instruments for monitoring the condition of a vehicle's shock absorbers, thereby increasing the safety of automobile driving. The suspension of a car is generally made from a spring and shock absorber assembly, the arrangement and construction of which are such as to give the best compromise between comfort and safety.
Generally, when a vehicle is new the driving safety, sometimes referred to as roadability, is good, but if trouble with the suspension damping elements occurs (i.e., wear or breakdown) a serious decline in the roadability can result. Very often, however, the average driver is unaware of the decline. Therefore, it is desirable to have a visual, simple and efficient monitoring means such as those available for tire pressure, for example, to monitor constantly the condition of the shock absorbers.
For a long time it has been possible to test shock absorbers with devices installed in garages or lines of general car inspection, but it is rare that the owner of a car has his shock absorbers inspected oftener than yearly, which leaves a long period during which a serious malfunction can occur and involve an accident. Therefore, it is in the driver's best interest to be informed continuously of the condition of the suspension damping system of his vehicle, and that is the purpose of the present invention.
In a typical car suspension, each wheel axle, or half-axle, is connected to the sprung mass (the body) through a spring (metallic or fluid) with which is associated a generally hydraulic shock absorber separate from the spring. The function of the shock absorber is to absorb a portion of the energy transmitted to or by the spring, usually by converting the energy to heat, and thereby the amplitude of relative vertical movements of the wheels and body.